We report a case of Klippel-Trenaunay syndrome (KTS) with serious morbidity caused by the rupture of hemangiomas of the spleen and inferior epigastric artery (IEA). A 40-year-old woman, who had suffered from edema and varicose veins in her left leg and toes since birth, underwent emergency laparotomy and splenectomy for a spontaneous splenic rupture. Pathological examination revealed hemangiomatosis of the spleen. She presented again 40 days later with a rectus muscle hematoma, which computed tomography revealed to be actively bleeding. Arteriography confirmed a bleeding IEA, which was then embolized. Hematological investigation revealed a heterozygous form of factor VIII and fibrinogen deficiency. The patient recovered well and was asymptomatic at her 1-year follow-up. We report this case to reinforce that investigations for KTS should involve all organ systems, and include detailed hematologic tests. By defining coagulation and vascular abnormalities, life-threatening bleeding episodes may be prevented.